Layer-by-layer assembly has been explored as a general approach for interface modification and engineering. In the recent past, increasing interest has been attracted for functional multilayered polyelectrolyte assemblies on biological cells. Here we summarize layer-by-layer polyelectrolyte/particles assembly on different kinds of cells, from microbes, such as fungi, bacteria and viruses, to mammal cells, and even for multicellular organisms. The toxicity of polyelectrolytes used in this process is evaluated and the mechanisms are also given in detail. Finally, conclusions and perspectives are given.